1. Faculty of Health Sciences, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa.
2. Medical Research Council of Zimbabwe, Ministry of Health and Child Welfare, Harare, Zimbabwe.
3. Letten Research Foundation, Harare, Zimbabwe.
4. Department of Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark
5. College of Health Sciences, University of Zimbabwe, Harare, Zimbabwe.
6. Division of Women and Children, Rikshospitalet Oslo University Hospital, Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
7. School of Public Health, University of California, Berkeley, California.
8. CESHAAR Research Centre, Harare, Zimbabwe.
9. Epidemiology and Strategic Information Unit, HIV/AIDS, STIs and TB (HAST), Human Sciences Research Council, Pretoria, South Africa.